Imprinting mechanism using rotational inertia to move type to printing position



Jan. 9, 1968 j w RYAN ET AL 3,362,517

IMPRINTING MECHANISM USING ROIATIONAL INERTIA TO MOVE TYPE TO PRINTING POSITION Original Filed Jan. 4, 1965 4 Sheets-Sheet 1 i/P/Pfn/ 9/15 4441947 J. W. RYAN ET AL IMPRINTING MECHANISM USING ROTATIONAL, INERTIA TO Jan. 9, 1968 MOVE TYPE TO PRINTING POSITION Original Filed Jan. 4, 1965 4 Sheets-Sheet 2 4470?! Fill kiaar ET AL Jan. 9, 1968 J. w. RYAN 3,362,517

IMPRINTING MECHANISM USING ROTATIONAL INERTIA' TO MOVE TYPE TO PRINTING POSITION Original Filed Jan. 4, 1965 4 Sheets-Sheet 5 Jan. 9, 1968 j w RYAN ET AL 3,362,517

IMPRINTING MECHANISM USING ROTATIONAL INERTIA TO MOVE TYPE TO PRINTING POSITION Original Filed Jan. 1, 1965 4 Sheets-Sheet 4 Awe-w Tv/is 12w (4/. FYI/V I 4 7' WK?! 9/; Ka /r United States Patent 6 Claims. or. 197-18) This application is a continuation of our application Ser. No 422,976, filed Jan. 4, 1965, now abandoned.

The invention relates to an imprinting mechanism and has a particular utility in that the mechanism is readily adaptable for incorporation in a toy typewriter designed for childrens use.

Toy typewriters have maintained a long-standing and consistent commercial position in the toy industry. Toy typewriters provide the inquisitive childs mind with a device which is a fascinating mechanical play thing and concurrently offer the parental advantage of insidious mental development and training' This multiple advanta ge is a patentreason for the long-standing and continuous commercial success of such devices.

Pursuasive though the above advantages may be, the commercial facts of life in the toy industry dictates certain axioms which in fact control toy typewriter design. The primary axiom is patent-economy. That is, the ultimate use of the device as a toy requires that it be produced and vended at a cost which 'is ridiculously low as compared to typewriting devices of commercial application. Postulating from the axiom of economy, it will be readily apparent that simplicity of design is a highly desirable feature.

A secondary, but none the less equally important axiom, requires that the product be durable. Prolonged and severe usage can obviously be anticipated. A design that does not present the advantage of durability would quickly fall into disrepute in the industry. Postulating from the requirement of durability, and closely related to the requirement of simplicity, it is generally advantageous that the typewriter design incorporate, in the overall combination, mechanical features adapted to provide long service life.

Lastly, but of major importance in view of the ultimate objectives of toy typewriters, the embodied design should be reliably operative. In this respect, prior art devices have often been found to be unreliable in service. Frequently typing mechanisms did not print reliably and accurately. Such a failure strikes at the heart of the main objectives of the equipment, namely, maintenance of the childs mental interest and the development of the childs intellectual capacity. The immature user usually becomes disheartened and discards the toy when his relatively simple objectives are not promptly achieved. Mechanical unreliability of the typewriting mechanism escapes the understanding of the immature mentality.

With the above in mind it is a general object of the disclosed invention to provide an imprinting mechanism particularly adaptable to incorporation within toy typewriting devices and offering the features of design simplicity with resulting economical production.

It is a further object of the invention to provide a device of the type here under consideration that offers the advantages of durability under the relatively severe service conditions imposed by children at play.

It is yet a further object of the invention to provide a design of an imprinting mechanism for the use here considered that couples with the mentioned design simplicity a high degree of operative reliability and thereby complements the important requirements of child occupation and intellectual development.

Specifically, the invention comprehends a printing type- Wheel of cylindrical, flywheel type construction, shaft mounted for rotatable movement. A plurality of characters to be imprinted are formed on the peripheral surface of the typewheel, said peripheral surface being positioned in operative relationship to a surface upon which imprinting is designed to take place. Inking means are provided in appropriate juxtaposition with the typewheel surface to supply the characters with imprinting fluid.

A power source is carried by the device and arranged to induce typewheel rotation. Specifically, the power source is in driving train relationship with the mentioned shaft upon which the flywheel type typewheel is mounted. In one embodiment of the invention, the driving train includes a clutch connection in series relationship therein. A particular feature of the clutch utilized in this embodiment, relates to the fact that it has a maximum torque transmitting capacity. That is to say, the clutch connection will transmit rotative energy to the typewheel under normal load condition thereof. If the typewheel is loaded beyond the predetermined level, clutch slippage is induced and the driving connection between the power source and the typewheel is broken. The slippage absorbs the driving energy of the power source without stalling the operation thereof.

In one embodiment of the invention, the typewheel, the power source and the connecting driving means are collectively frame mounted. The mounting frame carrying the mentioned apparatus, is supported for movement by a base frame, the latter being relatively fixed in space.

To control the imprinting operation, the typewheel arrangement has associated therewith a plurality of stops, each stop being in determined relationship with one of the characters peripherally arranged on the typewheel surface. Key operated mechanisms, of similar construction, are arranged to be selectively operated by the child and thereby engage one of the mentioned stops. The effect of engagement between the mechanism and the stop is to artificially load the typewheel, induce the mentioned clutch slippage and halt typewheel rotation. As a given stop halts typewheel rotation, its specific related character is stopped in imprinting position. Abrupt halting of typewheel rotation creates a reactive force which is applied against the entire apparatus frame structure pivotally carried by the first mentioned base of fixed frame and inducing movement of the pivoted frame. Frame movement brings the peripheral surface of the typewheel into imprinting engagement with the surface to be printed upon. The imprinting action absorbs the reactive force and provides a secondary reactive force to aid in returning the frame to its original and operating position. Supplemental means are available to aid this return movement. Upon release of the stopping mechanism, excessive typewheel loading is relieved thereby bringing the arrangement back within the torque transmitting capacity of the mentioned clutch. The clutch then picks up the typewheel load, inducing rotation thereof in the normal manner until one a of the mechanisms is again actuated to repeat the imprinting cycle.

An alternate construction illustrated again embodies a fly-wheel type imprinting typewheel appropriately justaposed to a surface upon which printing is to take place. The typewheel is shaft mounted for rotation on a first frame and, the first frame is pivotally carried by a fixed or base frame. A plurality of stop means comprising cams of naval form are mounted on the shaft for concurrent rotation therewith and with the type wheel. The fixed frame carries a plurality of flexible stop fingers in appropriate relation to the respective cams. Each finger embodies a first hook-like boss which is key biased into operative abutting relationship with a first cam lobe. As the first boss engages the first cam lobe, after key depression, the rotational movement of the cam lobe further flexes the finger to bring a second stop therein into interfering relationship with a second lobe on the cam. Engagement between the second boss and lobe halts typewheel rotation and a secondary reaction is produced to pivot the entire frame mechanism and the surface of the typewheel into printing contact with the mentioned surface. The alternate embodiment is provided with an additional mechanism to assure accurate placement of the selected character on the surface. Specifically, the annular inner surface of the imprinting typewheel is provided with a plurality of notches, each notch being in determined relation with one of the characters or letters appearing on the typewheel surface. A detent mechanism is carried by the movable frame for reciprocating movement relative to the frame in response to frame pivoting. The particular detent employed is spring biased by a resilient element carried by the fixed frame so that upon movement of the frame a dog tooth carried by the detent mechanism engages a particular notch on the inner surface of the typewheel. The interlock is maintained during pivoting or imprinting movement of the frame. Thus the detent mechanism accurately positions the selected character or letter in appropriate imprinting relation with the mentioned surface and assures uniform print application.

These and other advantages, objects, and features of the herein disclosed invention will become apparent in the course of the following description and from an examination of the related drawings, wherein:

FIGURE 1 is a perspective view of a typewriter employing the invention,

FIGURE 2 is a sectional view taken along line 22 of FIGURE 1,

FIGURE 3 is a fragmentary perspective view of a first embodiment of an imprinting mechanism, illustrating the general relationship of the operating components,

FIGURE 4 is a fragmentary sectional view similar to FIGURE 2, illustrating the mechanism in imprint initiation condition,

FIGURE 5 is a fragmentary sectional view similar to FIGURE 4, illustrating the mechanism. in imprinting position,

FIGURE 6 is a fragmentary sectional View, partly in elevation, taken along line 66 of FIGURE 3 and showing a detailed arrangement of a clutch employed in the first embodiment,

FIGURE 7 is a fragmentary perspective view of the surface of the imprinting platen taken along line 7-7 of FIGURE 2, illustrating the position of the characters thereon,

FIGURE 8 is a fragmentary perspective view, showing an alternate embodiment of the invention,

FIGURE 9 is a fragmentary sectional view taken along line 99 of FIGURE 8,

FIGURE 10 is a fragmentary sectional view, similar to FIGURE 9, illustrating the mechanism in imprint initiation condition,

FIGURE 11 is a fragmentary sectional view, similar to FIGURE 10, illustrating the mechanism in imprinting position,

FIGURE 12 is a fragmentary sectional view taken 4 along line 12-12 of FIGURE 8, showing the detent mechanism employed with the device in normal position before imprinting,

FIGURE 13 is a fragmentary sectional view, similar to FIGURE 12, illustrating the detent mechanism in imprinting position, and

FIGURE 14 is a fragmentary perspective view of the detent mechanism employed.

Describing the invention in detail and directing attention to FIGURE 1, it will be seen that the toy typewriter comprises a housing H carrying a keyboard K and carriage C around which a sheet of paper P may be rolled in the conventional manner.

Considering FIGURE 3, a fixed base frame It is provided. The base frame 10 comprises horizontal plate 12 and vertically upstanding plates 14, 14 at opposed edges thereof. A movable frame, indicated generally as 16, comprises the lower plate 18 and upstanding end plates 2%, 20 formed and arranged so that the entire movable frame 16 is in cradle reception between end plates 14-, 14 of the base frame 10. The movable frame 16, in the preferred embodiment of the invention, is carried for pivotal movement relative to the base frame 10 by virtue of the pins 22, 22 which interconnect the respective plates 14 and 20.

End plates 20 of the movable frame 16 extend upwardly above the base frame 10 to mount opposed ends of a longitudinally extending shaft 24. Collars 26, 26 are positioned immediately inboardly of the respective vertical plates 20 to maintain the shaft 24 in position within the moveable frame 16 and to provide shaft journals.

Intermediate collars 26 the shaft 24 carries, for rotation therewith, a flywheel type printing typewheel indicated generally at 28. The typewheel 28 is provided with an annular peripheral surface 30*, the latter having formed thereon, in upraised condition, a plurality of characters or indicia such as letters or numbers and as indicated by numeral 32 (see FIG. 7).

Completing the structure fixedly associated with shaft 24 and inboardly of the moveable frame 16, a spiral bar, indicated generally at 34 is provided extending radially outward of the surface of the shaft 24 and proceeding there-around in spiral or helical fashion. The bar 34- presents a plurality of stepped abutments 36,36 which are preferably uniformly formed and uniformly circumferentially and axially spaced about the longitudinal axis of the shaft 24.

It will be understood that each abutment 36 is in predetermined angular relationship to one of the indicia 32 (FIGS. 3 and 7) peripherally formed on the surface of the typewheel 28. The purpose of the relationship will hereinafter be more specifically described. While the abutments 36 are shown as integrally formed within the spiral bar 34 and that such structure offers the advantage of unitary strength, it will be understood that it is the relationship of the abutments 36 relative to the indicia 32 that constitutes the important operative feature of the invention. It will therefore be understood that any effective equivalent structure may be utilized.

An inking pad, 38, is carried for rotation on shaft 40 so that the surface thereof continually and rotationally engages the peripheral surface 30 of the printing typewheel 28. Thus a source of ink or other imprinting material for the upraised characters or indicia 32 is provided. The shaft 40 is fixedly carried (not shown) by the base frame 10.

The left hand segment of the structure shown in FIG URE 3, and directing attention to FIGURE 6, provides a reduced diameter segment 42 of the shaft 24- which extends through related plate 20 and carries, immediately adjacent the plate 20, female clutch collar 44. The collar 44 may be secured to the shaft segment 42 for rotation therewith in any conventional manner, as for example by set screw 46. The outer segment of collar 44 is provided with a clutch surface 48 of truncated conical form. A

driven gear 50 is carried for rotatable movement about the shaft segment 42 and includes a longitudinally elongated boss 52, the latter having clutch surface 54 again of truncated conical form to complement the clutch surface 48 on the collar 44. While the clutch surfaces of the preferred embodiment are shown to be of conical form it will be understood that a clutch surface of any physical configuration may be employed providing the functional requirements hereinafter described are fulfilled.

A shaft fixed collar 56 is carried by the segment 42 outboardly of the driven gear 50 and serves as an abutment for coil spring 58, the latter being compressively interposed between the collar 56 and the driven gear 50 to normally bias the gear 50 to the right (as seen in FIG. 6) and induce engagement of the clutch surfaces 48 and 54.

Returning to FIGURE 3, it will be seen that a power source supporting bracket 60 is conventionally secured, as for example by welding, to the outboard surface of plate and extends outwardly thereof to mount a power source indicated generally at 62. In the preferred embodiment the power source 62 maybe a conventional AC or DC electric motor but it will be understood that other power mechanisms may be employed. Power source 62 has an upwardly extending armature shaft 64 carrying, at the extremity thereof, a pinion or drive gear 66, the latter gear engaging the driven gear 58. The armature shaft 64 may also be provided with the minor fly-Wheel 68 to provide motion inertia during the action hereinafter described and thereby avoid stalling of the power source 62.

With the above described structure in mind, it will be apparent to those skilled in the art, that upon energizing of power source 62, rotation of the shaft 24 and the carried typewheel 28 will be induced via the driving train series incorporating the pinion gear 66, the driven gear 50 and the clutch surfaces 48 and 54, respectively. The entire arrangement will be driven in counter-clockwise direction as shown in FIGURE 2.

The imprinting device further incorporates a plurality of bell cranks 70, 70 fulcrumed for pivotal reciprocating motion about rod 72, the latter being carried (not shown) by the fixed frame 10. Each bell crank 78 has connected to the terminus of one of its arms, a link 74. The opposed end of each link 74, in turn, is connected to an actuating bar 76. Each bar 76 is pivoted to frame 18, as at 77 (see FIG. 2), and is integrally formed with a spring loaded key 79 of keyboard K.

It will be noted that each bell crank 78 is physically arranged in determined relation with one of the stops or abutments 36. Specifically, the free end of each bell crank arm 82, upon key depression and clockwise rotation of the crank, will move into position to engage related stop 36 and halt rotation of shaft 24. The imprinting surface 78, of paper P is positioned to surround a platen C drum and in operative imprinting relation with the peripheral surface 30 of the typewheel 28.

Tocause printing action, a selected key '79 is depressed. The motion of the bar 76 is transmitted, via connecting link 74, to the related bell crank 70 inducing the arm 82 thereof to rotate upwardly as seen in FIGURE 2 about the fulcrum 72. It will be recalled, that the shaft 24 and carried typewheel 28 are constantly rotating. As the bell crank arm 82 is pivotally raised into interfering relationship with the related stop 36, the stop 36 engages the end of the arm 82 with impact force and rotation of the shaft 24 is halted. This action is shown in FIGURE 4. The force applied against the bell crank arm 82 may be considered to be directed rightwardly as seen in FIGURE 4. Responsive to the impact force thus applied, an opposite reactive force is created which is applied against the moveable frame 16 and the entire structure carried thereby. Since the frame 16 is pivotally carried from the fixed frame 10, there is no immediate source of resistance to the reactive force, and, accordingly, the moveable frame 16 is induced to pivot about the pins 22 in a counter-clockwise direction as seen in FIGURES 4 and 5. Such motion brings the typewheel surface 30 into sharp contact with the paper surface 78 imprinting thereon the related character appearing on the surface of the typewheel 32. The imprinting action absorbs the reactive force heretofore mentioned and creates a secondary reactive force which tends to return the moveable frame 16 and carried structure in a clockwise direction to its original position. To aid in the clockwise return, a spring element 86 may be secured to the moveable frame 16 at one end thereof and have the other end secured to the fixed frame 10 as is shown in FIGURE 3.

Returning to FIGURE 5 it will be recalled that rotation of the shaft 24 is induced by virtue of the frictional engagement between the respective clutch surfaces 48 and 54 heretofore described. Upon excessive loading of the shaft 24 by movement of a bell crank arm 82 into stopping relationship with a related step 36, the surfaces 48 and 54 slip relative to each other thereby avoiding stalling of the power source 62. In this circumstance it will be apparent that the pinion 66 and driven gear 50 continue rotation even though shaft 24 is temporarily halted. Though slippage occurs at the clutch surfaces 48 and 54, it will be noted they are still in sliding frictional engagement. This sliding friction is effective to continue to transmit a torque load effective in the direction of typewheel and shaft rotation. This slip torque load acts as a brake on the halted shaft and typewheel to prevent same from rebounding in a counter-clockwise direction in response to the abrupt halt. Thus accurate halting of the selected indicia in proper imprinting position is assured.

After the imprinting operation, the bell crank 78 is allowed to pivot in a counter-clockwise direction withdrawing its arm 82 from interfering relationship with the related stop 36. With the excessive loading force removed, frictional engagement between the clutch surfaces 48 and 54 is again operative to overcome the inertia of rest of the shaft 24 and related structure and again induce shaft rotation.

Attention is now directed to the alternate embodiment illustrated in FIGURES 8 through 14 of the drawings. A fixed frame 90 again journally carries, as at 92, a pivoted frame, indicated generally at 94. The frame 94 is similar in construction to the first mentioned pivoting frame 28 and carries rotatable shaft 96 thereon. Adjacent one end thereof, the shaft 96 carries a driven wheel 98 and, spaced therefrom, a fly-wheel type printing typewheel 100. The typewheel 100 is provided with peripheral surface indicia as earlier described. A power source, such as conventional electric motor, 182, has a driving pinion 184 engageable with the surface of driven gear 98. The surfaces of the pinion 184 and driven wheel 98 may be covered with rubber material or the like to provide appropriate frictional engagement therebetween. The motor 182, in this embodiment, is preferably carried from the fixed frame 98. A platen C, identical to that described in the first embodiment, is fragmentarily shown in FIGURE 8 and arranged in appropriate printing relationship with the surface of platen 100. An inking pad 186 surface engages the platen 108. A plurality of stopping cams 108, 108 are mounted on, and distributed uniformly along, the shaft 96 for rotation therewith. A plurality of manually depressible key elements 118, 110 are positioned in operative relations with respective stop cams 108 as will hereinafter be described.

FIGURES 9 through 11 typically show the structure employed. Each key 110 is pivoted or fulcrumed to fixed frame 90 as at 112. The fixed frame 90 additionally carries post 114 which extends upwardly therefrom to mount one end of a flexible stop finger 116. Each flexible finger 116 comprises a generally horizontal segment 118 having a stop lug I28 protruding upwardly therefrom. The finger 116, at one end thereof, presents upwardly directed segment 122 having a shaft directed initiating boss on lug 124 projecting therefrom. The related key 110 has a projection 126 to abut the flexible finger 116 upon pivotal movement of the key 110 about the pivot 112.

Each cam N8 is provided with a pair of radially spaced lobes 130 and 132. It will be specifically noted that the cam lobe 136 has an engageable surface which falls in a plane which, if extended, as indicated by phantom line 134, is above the axis of rotation of shaft 96 (see FIG. 9). On the other hand, cam lobe 132 is provided with an actuating surface which falls in a plane which if extended intersects the axis of rotation of the shaft 96 as is evidenced by the phantom line 136.

In operation the key 111) is depressed. The projection 126 engages the lower surface of the finger 116, biasing the latter upwardly. As the finger 116 is urged upwardly, initiating boss 124 is brought into engagement with the initiating cam lobe 130 as shown in FIGURE 10. Continued rotation of the shaft $6 and initiating lobe 130 biases the fiexible finger 116 further upwardly and initiates a slight slow-down of the shaft 96 and related structure. The further biasing of the finger 116 brings stopping boss 120 into the line of rotation of the stopping cam lobe 132. Upon engagement between the lobe 132 and the boss 12% rotation of the shaft 96 and related structure is halted. The fact that plane 134 is non-aligned with shaft 96 means that slippage will occur before segment 122 is overstressed. However, sufficient contact will occur to flex finger 116 and bring boss 12!) into engagement with lobe 132. The impact load in finger 116 is therefore tensional minimizing opportunity for finger fracture.

The abrupt halt of the shaft 9-6 and related structure induces a reactive force which applied against the frame 94 causing pivotal rotation of the frame and carried structure about the axis of pivot 92 and in the direction of arrow 141). The typewheel 190 is brought into imprinting contact with the paper P and the printing action takes place. It will be noted that upon pivoting of frame 94- the stopping lug or boss 120 of the flexible finger 116 is disengaged from the stopping lobe 132 of the cam 138. The flexible finger then springs downwardly, in the direction of the arrow 142, out of interfering relationship with the cam 108 (see FIG. 11).

Another feature of this embodiment relates to the fact that upon clockwise pivoting of the frame 94, the surface of the driven wheel 98 disengages the driving pinion 104. Driving contact is re-established upon return of frame 94.

To assure accurate halting of the typewheel 100 and printing uniformity as the structure provides a detent mechanism, indicated generally at 144 in FIGURES 12 through 14. The typewheel wheel 100 is cavitied on one side thereof as at 146. The wall defining the cavity 146 has peripherally formed therearound a plurality of notches 148. Each notch 148 is in accurate predetermined alignment with a given character or indicia on the surface of the typewheel 100.

The frame 94 carries member 150 which in turn defines an elongated slot 152, the long axis of which intersects the axis of rotation of the shaft 96. A dog body 154 is carried, by the pin washer assembly 156, for sliding reciprocating movement within the slot 152. The dog body 154 has a radially outwardly projecting dog tooth 158 formed to complement the configuration of notches 148 formed in the typewheel 100. A wire element 161 projects from the dog body 154- outwardly of the typewheel 1th) and is interposed between a stopping lug 162 and a cantilever spring 164, both of which may be carried by the fixed frame 90.

In the normal position of the frame 94, as shown in FIGURE 12, the projecting element 161) abuts the stop lug 162 driving the dog body radially inwardly so that the dog tooth 158 will not engage a notch 148. As the frame 94 is pivoted, as above described, the movement thereof is counter-clockwise to position shown in FIG- URE 13. Upon such counter-clockwise pivot movement the projecting element 160 disengages lug 162. The spring 164 biases the element 160 and connected dog body 154 to the right, as seen in FIGURE 13, causing dog tooth 158 to engage adjacent notch 148 of the typewheel 1110.

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Thus as the typewheel is biased to imprinting position of FIGURE 13, the detent mechanism 144 accurately aligns the surface of the typewheel relative to the paper surface and maintains the typewheel in alignment during the entire imprinting operation. After imprinting, the frame 94 returns to normal position, projecting element engages the stop lug 162 and the dog body 154 is biased withdrawing dog tooth 158 from the notch 148. Pinion 1%4 again engages wheel 98 and platen and shaft rotation commences.

Patently, the invention as disclosed illustrate devices particularly adapted to incorporation in toy typewriters and offers that application the necessary advantages of economy, durability and reliability in service.

The invention as shown is by way of illustration and not limitation and maybe subject to various modifications without departing from the scope of the appended claims.

What is claimed is:

1. In an imprinting mechanism, a base, an imprinting typewheel having rotational inertia mounted for rotational movement about the axis of a shaft carried by said base, means on said base to accommodate secondary reciprocating movement of said typewheel relative to said base, means on said base disposed on one side of said typewheel for supporting an article to be imprinted, and means on said base for selectively and abruptly halting rotational movement of said typewheel in a selected position of rotation and serving as a reactive abutment, whereby rotational inertia of said typewheel creates a reactive force of sufficient magnitude to induce said secondary movement of said typewheel in a direction away from said halting means and towards said supporting means to bring said typewheel into imprinting engagement with the article on said supporting means, said halting means includes a plurality of notches on the typewheel, each of said notches being in predetermined relation with indicia on the typewheel, and movable detent means carried in operative relation with the notches, said detent means being movable into typewheel locking relation with the respective notches in response to said secondary movement to maintain a predetermined indicia in a predetermined position upon movement of the typewheel into said imprinting position.

2. An imprinting mechanism according to claim 1, wherein said detent means comprises a reciprocating dog body having a dog tooth arranged to engage said notches, abutment means on the body and base which are normally engageable to move said body and carried tooth out of notch engaging position, and secondary abutment means carried by the base and engageable with said body abutment means and operative to move said body and carried tooth into notch engaging position in response to initiation of said secondary movement.

3. An imprinting mechanism according to claim 2, wherein said secondary abutment means is a resilient spring element.

4. An imprinting mechanism according to claim 2, wherein said halting means further includes cam means having abutment lobes thereon and rotatable with said shaft, flexible finger means carried by the base and having abutment bosses thereon, said finger means being manually movable to bring the bosses and lobes into interfering relation and thereby effect initial halting of rotational movement of the shaft and typewheel.

5. An imprinting mechanism according to claim 4, wherein said imprinting means is adaptable to a typewriter, said finger means being movable in response to manual movement of a typewriter key, said finger means having a pair of bosses thereon, said cam means having a pair of lobes thereon, the first of said bosses being movable into abutting engagement with the first of said lobes, whereby rotational movement of said cam means induces further flexing of said finger means to bring the second of said bosses into abutting relation with the second of said lobes.

References Cited UNITED STATES PATENTS McKittrick 19718 Brooks 19718 Ferguson 197-18 XR 1 Ferguson 19718 XR Richards 197--18 10 1,453,867 5/1923 Fanslow 1976.4 2,067,821 1/1937 Bell 19720 2,311,737 2/ 1937 Colombo 19718 2,365,913 12/1944 Stenfors 197--18 5 2,870,897 1/1959 Hubl 19718 OTHER REFERENCES I.B.M. Technical Disclosure Bulletin, Keyboard and Print Wheel Entry by C. A. Foot, vol. 5, No. 2, July 1962, p. 31.

ROBERT E. PULFREY, Primary Examiner.

E. S. BURR, Examiner. 

1. IN AN IMPRINTING MECHANISM, A BASE, AN IMPRINTING TYPEWHEEL HAVING ROTATIONAL INERTIA MOUNTED FOR ROTATIONAL MOVEMENT ABOUT THE AXIS OF A SHAFT CARRIED BY SAID BASE, MEANS ON SAID BASE TO ACCOMMODATE SECONDARY RECIPROCATING MOVEMENT OF SAID TYPEWHEEL RELATIVE TO SAID BASE, MEANS ON SAID BASE DISPOSED ON ONE SIDE OF SAID TYPEWHEEL FOR SUPPORTING AN ARTICLE TO BE IMPRINTED, AND MEANS ON SAID BASE FOR SELECTIVELY AND ABRUPTLY HALTING ROTATIONAL MOVEMENT OF SAID TYPEWHEEL IN A SELECTED POSITION OF ROTATION AND SERVING AS A REACTIVE ABUTMENT WHEREBY ROTATIONAL INERTIA OF SAID TYPEWHEEL CREATES A REACTIVE FORCE OF SUFFICIENT MAGNITUDE TO INDUCE SAID SECONDARY MOVEMENT OF SAID TYPEWHEEL IN A DIRECTION AWAY FROM SAID HALTING MEANS AND TOWARDS SAID SUPPORTING MEANS TO BRING SAID TYPEWHEEL INTO IMPRINTING ENGAGEMENT WITH THE ARTICLE ON SAID SUPPORTING MEANS, SAID HALTING MEANS INCLUDES A PLURALITY OF NOTCHES ON THE TYPEWHEEL, EACH OF SAID NOTCHES BEING IN PREDETERMINED RELATION WITH INDICIA ON THE TYPEWHEEL, AND REMOVABLE DETENT MEANS CARRIED IN OPERATIVE RELATION WITH THE NOTCHES, SAID DETENT MEANS BEING MOVABLE INTO TYPEWHEEL LOCKING RELATION WITH THE RESPECTIVE NOTCHES IN RESPONSE TO SAID SECONDARY MOVEMENT TO MAINTAIN A PREDETERMINED INDICIA IN A PREDETERMINED POSITION UPON MOVEMENT OF THE TYPEWHEEL INTO SAID IMPRINTING POSITION. 